This invention relates to a dental or medical impression composition, and more particularly, to an alginate impression composition that is hydrophilic.
Alginate impression materials are well known in the art and are used in both dentistry and medicine. In dentistry, alginate impression materials are used to take impressions of teeth in orthodontics, prosthodontics, and other dental practices.
In addition, alginates are particularly useful in medical procedures, such as maxillofacial reconstruction. Specifically, impressions are taken after a surgical procedure is performed, and the surgically injured tissues have healed.
In general, an alginate impression material is mixed with water and allowed to set for 2 to 15 minutes. Conventional alginate impression materials are hydrophobic, thus requiring vigorous mixing of the alginate/water mixture following the addition of water. After thorough mixing, a homogenous material is obtained, which is used to make the desired impression.
Since conventional alginate impression materials are hydrophobic, when dental impressions are taken, the applied teeth must be substantially dry. This is sometimes very difficult for the dental practitioner to achieve, resulting in imperfections associated with the dental impression.
In addition, because of the hydrophobic nature of the alginate impression material, a higher water to powder ratio has to be used. This is because a greater quantity of water is required in order to facilitate manipulation of the impression material. As a result, the alginate matrix in the material is weaker than desired. Thus, storage and use of a conventional alginate impression material are made rather difficult.
Furthermore, when water is added to the alginate powder, since the material is hydrophobic, it becomes much more difficult for the practitioner to achieve complete incorporation or absorption of the water into the material. In turn, preparation of a dental or medical impression is made difficult.
Moreover, in surgical procedures, because the eventual prosthesis is often held in by undercuts in the surgical site, it is advantageous to have an alginate impression material that is strong, flexible enough to accurately record all internal surface architecture, and with the ability to free itself from the undercut without tearing upon removal from the site. However, conventional alginate materials have been too weak to consistently offer these desirable properties.
Accordingly, it would be desirable to provide a dental or medical alginate impression composition that overcomes the above-identified disadvantages.